A21- Questions and Responses 2.pdf

Question # Question Response

Regarding the Hatteras Ferry and Rollinson Channel: Does the 60-day period of performance mean USACE wants a final report to be delivered for that portion of the project, or will a draft dataset be sufficient?

The 60 Day time period for the Rollinson Channel will include: DRAFT boring logs with visual USCS soil classification of logged stratigraphy/lithology Location, X, Y, Z. We know the lab testing will take a while to complete, the lab test results are not part of the 60-day submittal. Only the boring logs for the Rollinson-Hatteras Ferry Channel portion of the job.

Is Bentley OpenGround Cloud required for generating drill logs, or will gINT suffice as used in previous USACE Vibracore projects?

USACE has migrated away from gINT and Bentley no longer supports gINT (for USACE). Therefore, all geotechnical work (boring logs) is to be put into OpenGround.

Is there an anticipated award date for this project?

USACE is going to make an effort to award within 15 days of the quote due date.

Could the district provide an Activity Description and Timeline Table for the Hatteras Ferry-

Rollinson Channel project (60-day timeline), similar to the table included for the Big Foot

Slough-Silver Lake Harbor 180-day leg of the project (Table 3, Page 11 of the SOW)?

According to Table #3, all work shall be completed within 180 days of contract award. However, per the first paragraph of I.

General Requirements, Hatteras Ferry-Rollinson Channel vibracore collection and submission of draft drillings shall be completed within 60 days of the 180-day total.

Do all vibracores for both projects need to be collected prior to USACE’s lab sample selections, or can vibracore collection and sample analysis begin concurrently to expedite scheduling?

The USACE sample selection process can occur as vibracores and respective draft logs are completed. Thus, while USACE evaluates the draft logs and makes sample determinations, the contractor may continue with on-site vibracoring fieldwork.

Additionally, after USACE sample selection of presented logs has been completed, lab analysis can commence while fieldwork continues.

Regarding vibracore sampling (Page 4 of the SOW), please confirm that only one (1) additional vibracore attempt is required if refusal is encountered (i.e. if refusal is encountered, we are required to offset up to 20 feet and attempt one (1) more additional vibracore at a separate location within 20 horizontal feet of the original point, and if refusal occurs again, we will record both locations and notify USACE.)

Correct. From the SOW, page 4:"...The recovered sediments in each vibracore should not be less than 75% of penetration/drive length unless the collected vibracore encounters refusal. To document vibracore refusal, penetrometer data collection shall be recorded and presented to verify vibracore refusal. Vibracore refusal is defined as the sampling barrel having a penetration rate of less than 0.2 feet over a 30-second period. If vibracore refusal is encountered at the seabed, the Contractor shall offset up to 20 feet and conduct an additional vibracore attempt at a separate location within 20 horizontal feet of the original point.

Location information and refusal depth shall be recorded for each location where refusal is encountered."

Clarification on Cloud-Based System: Could you confirm whether Bentley OpenGround Cloud is the required system for data submission, or are we able to use any geotechnical data management system?

ANSWER: Per the SOW: "All drilling logs shall be developed using USACE Bentley OpenGround Cloud configured for the project.

USACE will provide necessary permissions to Contractors entering data. If the Contractor does not already have a license for

OpenGround Cloud, the Contractor must obtain user-specific "named user" or concurrent licenses." REASONING: USACE is migrating away from gINT because Bentley has stopped all technical support for gINT. HQUSACE has determined that

OpenGround will be the geotechnical software used by the entire ACE for production of drilling logs, cross sections, etc.

Questions and Responses

Solicitaiton Number: W912PM25QA001, Rollinson and Hatteras Vibracore Testing

Shallow Water Drilling Procedures:In the event that certain sampling locations have water depths too low for standard drilling equipment, what steps should be taken?

* Would it be acceptable to: * Attempt alternative drilling methods (e.g., smaller barge-mounted rigs, hand coring, or push-probe methods)?

* Relocate the drilling point within an allowable buffer range (e.g., 10-20 feet)?

* Submit documentation and request approval for any location that may be inaccessible?

Per the SOW, "Vibracore Sampling": "...Vibracores shall be performed within 150-feet (horizontally), yet as close as practicable to, the locations provided by the Wilmington District (Tables 1 and 2).

"...Vibracore drilling shall be accomplished by vibrating a vertical 3-inch diameter sampling tube to the run length (10- or 20-feet) designated for each vibracore, as shown in Tables 1 and 2. Per the South Atlantic Regional Biological Opinion (SARBO) for the Endangered Species Act, the vibracore sampler shall not be operated until the vibracore platform contacts the seafloor/channel bottom and vibracore barrel contacts the seafloor/channel bottom. The vibracore sampler shall not be operated during retrieval operations (SARBO, 2020). The recovered sediments in each vibracore should not be less than 75% of penetration/drive length unless the collected vibracore encounters refusal. To document vibracore refusal, penetrometer data collection shall be recorded and presented to verify vibracore refusal. Vibracore refusal is defined as the sampling barrel having a penetration rate of less than 0.2 feet over a 30-second period. If vibracore refusal is encountered at the seabed, the

Contractor shall offset up to 20 feet and conduct an additional vibracore attempt at a separate location within 20 horizontal feet of the original point. Location information and refusal depth shall be recorded for each location where refusal is encountered."

"...Life safety concerns encompass issues or situations directly jeopardizing physical safety and well-being. Given the dynamic nature of the project area, which includes factors such as shallow water, tidal influence, shifting shoals, and exposure to swell, if access to a vibracore location becomes impossible due to life safety concerns, immediate communication between the COR, KO, and the contractor's project manager is required to assess the need for location abandonment. The contractor shall initiate communication via phone to the COR and via writing to both the COR and KO, detailing the encountered conditions during the attempt to access the respective vibracore location. Additionally, the contractor shall coordinate between the vibracoring vessel captain, the contractor’s project manager, and the Government to determine the location of an alternate vibracore within the project area. Tube lengths associated with the vibracores in Tables 1 and 2 will not change even if the original locations are moved elsewhere. Conversely, if an alternate location which supports the Government’s project goals is not determined, no alternative vibracore shall be collected and the contractor shall not receive payment for the collection, logging, or photographing of that respective vibracore."